ROY F. CHEMALY, MD, MPH, FIDSA, FACP PROFESSOR OF MEDICINE DIRECTOR, INFECTION CONTROL SECTION DIRECTOR, ANTIMICROBIAL STEWARDSHIP PROGRAM The Challenges.

ROY F. CHEMALY, MD, MPH, FIDSA, FACPPROFESSOR OF MEDICINE

DIRECTOR, INFECTION CONTROL SECTIONDIRECTOR, ANTIMICROBIAL STEWARDSHIP PROGRAM

The Challenges and Pitfalls in Diagnosing or Misdiagnosing Tuberculosis: Are the Days of

TB Skin Tests Over?

Disclosures

• Consultant for Oxford Immunotec

Outline• Background

• Population at Risk

• Clinical implications

• Different TB Screening Strategies

• IGRAs in Special Patient Populations

Tuberculosis Landscape

1. World Health Organization (WHO). Global Tuberculosis Report 2014.2. www.cdc.gov/TB/topic/globaltb/default.htm. 3. www.cdc.gov/tb/events/worldtbday/history.htm.

TB in the US: 2013 Data1

• 9588 new TB cases in US (case rate of 3.0)

• TB rate among foreign-born (FB) was 13x higher than US-born

• 4 states account for ½ of all reported cases: – California– Texas – New York – Florida

1. Centers for Disease Control and Prevention. Trends in Tuberculosis – United States, 2013. MMWR. 2014.

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Public Health Concerns• Every 100 contacts not treated will lead to 3 new

cases of TB in 1−2 years.

“Initiatives that promote further TB awareness, testing, and treatment of latent infection and TB disease among foreign-born persons and racial/ethnic minorities will be critical for future TB elimination efforts.”

Fox GJ, et al. Eur Respir J. 2013;41:140-156.Centers for Disease Control and Prevention. www.cdc.gov/mmwr/preview/mmwrhtml/mm6211a2.htm?s_cid=mm6211a2_e.

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LTBI to Active TB Progression

Core curriculum on Tuberculosis: What the clinician should know. 5th ed. Atlanta, GA: US Department of Health and Human Services, CDC, 2011.

Timeline of Advancements in TB Screening

1907 – Tuberculin skin test developed by Dr. Charles Mantoux

2001 – US launch of QuantiFERON®-TB

2004 – US launch of QuantiFERON®-TB Gold

2007 – US launch of QuantiFERON®-TB Gold (In-Tube Version)

2010 – US launch of approved overnight storage protocol for the T-SPOT®.TB test

1900 2000

2008 – US launch of the

T-SPOT®.TB test

2009 - US launch of Oxford Diagnostics Laboratories; the only national lab dedicated exclusively to the T-SPOT.TB test

Blood Collection for QFT® Testing• Collection tubes include:

– Nil control (grey cap)– TB antigen (red cap)– Mitogen control (purple cap)

• Tubes require shaking (10x each) to mix blood with antigens coated on the inside of the tubes, but too much shaking could cause aberrant results.

• Blood in collection tubes must be incubated for 16−24 hours at 37°C within 16 hours of collection.2,3

1. QuantiFERON-TB Gold Package Insert. Cellestis, Inc. Valencia, CA. Doc. No. US05990301L, March 2013.2. Herrera V, et al. J Clin Microbiol. 2010;48(8):2672-2676. 3. Doberne D, et al. J Clin Microbiol. 2011;49(8):3061-3064.QFT is a registered trademark of Cellestis, Inc.

Interpreting QFT® Results

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1. QuantiFERON-TB Gold Package Insert. Cellestis, Inc. Valencia, CA. Doc. No. US05990301L, March 2013.QFT is a registered trademark of Cellestis, Inc.

QFT Result Nil(IU/mL) TB Ag-Nil (IU/mL) Mitogen-Nil

(IU/mL)

Positive < 8.0 > 0.35 and > 25% Nil value Any

Negative < 8.0 < 0.35 > 0.5

Indeterminate < 8.0 > 0.35 and < 25% of Nil value < 0.5

Indeterminate > 8.0 Any Any

Blood Collection for T-SPOT®.TB• Standard phlebotomy techniques• Uses a standard lithium or sodium heparin tube• Less sensitive to preanalytical variables than QFT®

– Time from collection to analysis– No specialized tubes needed– No specific order of draw– No shaking of tubes– No incubation required – Specimens maintained at room temperature

for up to 32 hours

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1. T-SPOT.TB Package Insert. Marlborough, MA: Oxford Immunotec; 2013.T-SPOT is a registered trademark of Oxford Immunotec, Ltd. QFT is a registered trademark of Cellestis, Inc.

The Science Behind T-SPOT®.TB Technology1

• Density gradient isolation of mononuclear cells• Quantitation of cells and adjustment of concentration• Incubation with specific antigens on ELISPOT microtiter plate

1. T-SPOT.TB Package Insert. Marlborough, MA: Oxford Immunotec; 2013.Ficoll and Ficoll-Paque are trademarks of GE Healthcare, Ltd. T-SPOT is a registered trademark of Oxford Immunotec, Ltd.

Plate Bottom

IFN

Interpreting T-SPOT®.TB Results

1. T-SPOT.TB Package Insert. Marlborough, MA: Oxford Immunotec; 2013. T-SPOT is a registered trademark of Oxford Immunotec, Ltd.

Negative Result Positive Result

Nil Control

ESAT-6Panel A

CFP10Panel B

Positive Control

Interpreting T-SPOT®.TB Results

• The test result is Positive if Panel A-Nil and/or Panel B-Nil ≥ 8 spots.

• The test result is Borderline (equivocal) where the higher of Panel A-Nil or Panel B-Nil spot count is 5, 6, or 7 and retesting by collecting another sample is recommended.

• The test result is Negative if Panel A-Nil and/or Panel B-Nil ≤ 4 spots. This includes values less than zero.

• The test is invalid if mitogen < 20 spots or Nil > 10 spots.

1. T-SPOT.TB Package Insert. Marlborough, MA: Oxford Immunotec; 2013. T-SPOT is a registered trademark of Oxford Immunotec, Ltd.

Commercially Available IGRAsQuantiFERON®-TB Gold (In-Tube)1

•ELISA technology•Measures IFN-γ release•“One and done”•PI sensitivity: 88.2%•PI specificity: 99.1%•“Real-world” specificity: 98%−98.9%3,4

•3 specialized tubes•Provides qualitative results•No FDA-approved borderline category•Sample stability: 16 hours•Can be run in hospital lab•Available nationally through reference laboratories (eg, Quest)

The T-SPOT®.TB Test2

ELISPOT technologyEnumerates effector T cells“One and done”PI sensitivity: 95.6%PI specificity: 97.1%“Real-world” specificity: 98.9%−99.1%5,6

1 standard tubeProvides quantitative and qualitative resultsFDA-approved borderline categorySample stability: 32 hoursCan be run in hospital labAvailable nationally through Oxford Diagnostic Laboratories

1. QuantiFERON-TB Gold Package Insert. Cellestis, Inc. Valencia, CA. Doc. No. US05990301K, July 2011.2. T-SPOT.TB Package Insert. Marlborough, MA: Oxford Immunotec; 2010. 3. Schablon A, et al. BMC Infect Dis. 2011;(11):245-252. 4. Pai M, et al. Ann Intern Med. 2008;149:1-9.

5. Wang SH, et al. Scand J Infect Dis. 2010 Dec;42(11-12):845-850. 6. Bienek DR, et al. Int J Tuberc Lung Dis. 2009 Nov;13(11):1416-1421.T-SPOT is a registered trademark of Oxford Immunotec, Ltd.QuantiFERON is a registered trademark of Cellestis, Inc.

Tuberculin Skin Test (TST) vs Interferon-Gamma Release Assays (IGRAs)

TST•2 visits required (minimum)•Method: injection into skin•Results affected by BCG•Results in 48−72 hours•Subjective results•Costs unstable

IGRAs•1 visit required•Method: blood draw•Results not affected by BCG•Next-day results•Objective results•Costs defined and stable

Clinical Implications with a Suboptimal Testing

Case Study• 41-year-old Indian male with no known history of cancer who was referred

to us because of pneumonia. The patient is a nurse at MD Anderson Cancer Center who started working in September 2012.

• PMHx: February 2012, he started having a cough with off and on sputum production. He was diagnosed with bronchitis and received 2 courses of azithromycin with no improvement.

• He was referred to a Pulmonologist and a chest x-ray and a PPD skin test were done in March 2012, which were both negative. He received cefuroxime and later on Levaquin with no improvement.

• At that point, he was diagnosed with possible asthma and he was started on inhaled steroids.

• His cough got a little bit better initially and started to get worse again.

Case Study• Meanwhile, patient was hired and started his work at

MD Anderson in September 2012.

• He had a PPD skin test done in 2 steps and was read as negative.

• December 2012: Worsening cough and hemoptysis now.

• He saw another pulmonologist on the outside in February 2013 for a second opinion. No chest x-ray was done. The patient was prescribed another course of an antibiotic with no improvement.

Case Study

• Past Social History: – Born and raised in India. He immigrated to Canada in

2005 and then moved to the US few years later. – Working at MD Anderson since September 2012 as a

nurse on the Stem Cell Transplant Units. – Exposure to an active case of TB 35 years ago when he

was a child (his uncle had active TB). – The patient had multiple PPD skin tests which were

negative. He received the BCG vaccine as well. – He is married and he has 2 kids (9-month-old & 6 y.o).

Case Study

• May 2013: he went back to India for vacation. He saw an internist who did a Ziehl-Neelsen stain on 3 sputum specimens which came back positive for AFB. His chest x-ray showed bilateral infiltrates.

Baseline CT Scan of Chest on 5/2013

Confirmation of Diagnosis

•SEQUENCE IDENTIFICATION

•COLLECTED: 05/31/2013 ; 0610

• SOURCE: SPUTUM

•Primary Panel for Mycobacterium tuberculosis (MTB) by Broth Method

•Susceptibility testing:

•ANTIBIOTICS.......Concentration.....Interpretations....

•=======================================================

•Ethambutol.........(5.0)mcg/mL............... S

•Ethambutol.........(8.0)mcg/mL............... S

•Isoniazid..........(0.1)mcg/mL............... S

•Isoniazid..........(0.4)mcg/mL............... S

•Pyrazinamide.......(300)mcg/mL.............. S

•Rifampin...........(1.0)mcg/mL............... S

•=======================================================

•---------------------- FINAL REPORT ------------------------

•MYCOBACTERIUM TUBERCULOSIS COMPLEX (MY TBC)! from AFB

•Culture on same accession number.

•Identified by 16S ribosomal DNA sequencing.

•DIRECT SPECIMEN AFB SMEAR

•DIRECT SPECIMEN AFB SMEAR ACC# 13-151-05296

• COLLECTED: 05/31/2013 ; 0610 STARTED: 05/31/2013 ; 1201

• SOURCE: SPUTUM 05/31/2013 1631

•FEW TO MODERATE ACID FAST BACILLI SEEN IN DIRECT SMEAR!

5/2013; before therapy 10/2013; while on therapy

Issues Affecting TST Utility• False-Positive Results

– Foreign-born persons (BCG vaccinated) account for 60% of all TB cases in US– Exposure to other mycobacteria– Unknown cause

• False-Negative Results– Miliary TB– Immunosuppression

• AIDS• Cancer• Anti-TNF• Transplant

• Noncompliance– Failure to return for TST interpretation

Centers for Disease Control and Prevention. MMWR Morb Mortal Wkly Rep. 2010;59:291.

IGRAs in Special Patient Population

Case Study

• A 57-year-old male with high-risk ALL on hyper-CVAD off protocol with CNS involvement.

• He was seen initially by Infectious Diseases for right upper lobe opacities, chronic in nature with no associated symptoms, seen on repeated chest x rays over 3 months period.

Case Study

• Past social history: He is originally from Vietnam and has been in the US since 2007. He had a TB skin test when he came to the US and was negative reportedly. He denies exposure to anyone with TB.

• Past medical and surgical history were non significant except for newly diagnosed ALL.

• ID recommended: CT scan of chest, QuantiFERON®-TB Gold

test, galactomannan assay, fungal serologies, serum Cryptococcus antigen, and pulmonary consult for bronchoscopy.

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1. CT scan of chest: Chronic appearing opacities in RUL and lingular segment consistent with residual prior inflammatory change. No acute inflammatory process demonstrated. No effusion.

2. QuantiFERON®-TB Gold test: Indeterminate

3. Cryptococcus antigen, fungal serologies, and galactomannan assay were all negative

4. Evaluated by a pulmonologist and a bronchoscopy was not recommended as patient was completely asymptomatic with no evidence of an acute process.

Case Study

• One month later, patient developed fevers at home approximately for 1 week prior to presentation. He has been having occasionally chills.

• ROS: Denies shortness of breath, chest pain, nausea, vomiting, diarrhea, headaches, or cough.

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CT scan of chest: New consolidation in the left upper lobe with areas of cavitation is noted. New airspace disease in the right upper lobe is noted. New small left pleural effusion is seen. Emphysematous changes are present. No mediastinal or hilar adenopathy is seen.

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T-SPOT TUBERCULOSIS POSITIVE *

RESULTS FOR TEST CONTROLS:

NIL CONTROL:0

PANEL A:10

PANEL B:TMTC

POSITIVE CONTROL:TMTC

NOTE: TMTC INDICATES TOO MANY SPOTS TO COUNT

SAT INDICATES SATURATED WITH TOO MANY SPOTS

RESULTS INTERPRETATION:

RESULTS ARE NEGATIVE WHEN (PANEL A-NIL) OR (PANEL B-NIL)<=4 SPOTS,

INCLUDING VALUES LESS THAN ZERO.

RESULTS ARE POSITIVE WHEN (PANEL A-NIL) OR (PANEL B-NIL)>=8 SPOTS.

RESULTS ARE BORDERLINE WHEN EITHER (PANEL A-NIL) OR (PANEL B-NIL)=5,6,OR 7.

Case Study

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Confirmation of DiagnosisACID FAST BACILLI CULTURE

SOURCE: SPUTUM

------------------- SUPPLEMENTARY REPORT -------------------

ACID FAST BACILLI Isolated! Identification confirmed as:

MYCOBACTERIUM TUBERCULOSIS COMPLEX (MY TBC)!

Antimicrobial Susceptibility, Mycobacterium tuberculosis Complex, Broth Method

Susceptibility testing performed by:

MAYO Medical Laboratories, Rochester Campus

3050 Superior Drive NW

Rochester, MN 55901, 1(800)533-1710

ANTIBIOTICS.......Concentration.....Interpretations....

=======================================================

Ethambutol.........(5.0)mcg/mL............... S

Ethambutol.........(8.0)mcg/mL............... S

Isoniazid..........(0.1)mcg/mL............... S

Isoniazid..........(0.4)mcg/mL............... S

Pyrazinamide.......(300)mcg/mL............... S

Rifampin...........(1.0)mcg/mL............... S

=======================================================

Interpretation: S=Susceptible, I=Intermediate, R=Resistant,

N=Not Susceptible, D=Dose Dependent Susceptible

The Impact on his Care• Started on RIPE and followed under DOT.• Evaluation for Hematopoeitic Stem Cell

Transplantation was delayed.• After completing 4 cycles of hyper-CVAD, he was

found to have persistent high white count with CNS disease.

• A bone marrow biopsy was done and revealed 53% blast.

• At that time, the patient was started on EPZ-5676 on protocol.

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US Immunocompromised Population

Condition Estimated # of US Persons Living with Condition

HIV infection 1.2 million Rheumatoid arthritis 1.5 million Inflammatory bowel disease 1.1 million Systemic lupus erythematosus 320,000 Systemic sclerosis 49,000 Spondyloarthropathies 2.4 million Vasculitis 1.0 million End-stage renal disease 0.87 million Hematologic malignancies 1.0 million Solid organ transplant candidates 120,000

Total 10 million

1. Redelman-Sidi G, Sepkowitz K. Am J Respir Crit Care Med. 2013;188(4):422-431.

Patient Population CDC Guidelines Comments

HIV-infected persons• Consider sequential testing with TST and an IGRA in high-risk patients†

• Any positive result should be considered evidence of LTBI

• TST performance is limited in patients with CD4+ cell count < 200 cells/mm3

• Correlation between IGRAs and clinical risk factors for LTBI: strong evidence

• Increased likelihood of indeterminate results for both IGRAs

• T-SPOT.TB performance less affected by low CD4+ lymphocyte count

Redelman-Sidi G, Sepkowitz K. Am J Respir Crit Care Med. 2013 Aug 15;188(4):422-31.

TB Screening for HIV Patients for LTBI

• 275 patients had results for all 3 tests (QFT® and T-SPOT®.TB and TST)

• Patients with QFT-Gold positive results had higher CD4 cell counts

• T-SPOT.TB results were independent of CD4 cell counts• Agreement between the 2 IGRAs was poor

Stephan C, Wolf T, Goetsch U, et al. AIDS. 2008;22:2471-2479.

TST (n = 275)

QFT (n = 275)

T-SPOT.TB(n = 275)

Positive 33 52 66

Negative 243 222 201

Indeterminate NA 1 NA

[Invalid] NA NA 8

High Risk for TB Reactivation in HIV+ Patients

Performance of T-SPOT®.TB test for aid in diagnosis of active/probable TB in HIV-1 patients

Clark SA, Martin SL, Pozniak A, et al. Clin Exp Immunol. 2007;150:238-244.

Patient Group No. Sensitivity Specificity

All HIV w/ active/probable TB 30 90.3% 100%

CD4 T-cell count < 300 cells/µL 22 95.4% 100%

CD4 T-cell count < 200 cells/µL 14 92.9% 100%

CD4 T-cell count < 100 cells/µL 8 87.5% 100%

NPV of the assay for the diagnosis of active TB in HIV pts with clinical and radiologic signs of infection was 98.2%

Starke J et al. Pediatrics, 2014;134:e1763–e1773

Patient Population CDC Guidelines Comments

Patients with hematologic malignancy, including HSCT candidates

• Consider sequential testing with TST and an IGRA in high-risk patients• Any positive result should be considered evidence of LTBI

• TST performance is limited• Correlation between IGRAs and clinical risk factors for LTBI: weak evidence• T-SPOT.TB may be less affected by presence of neutropenia and/or lymphopenia and may be preferable

Redelman-Sidi G, Sepkowitz K. Am J Respir Crit Care Med. 2013 Aug 15;188(4):422-31.

Hematological Malignancies

• 95 patients had testing with TST, QFT-GIT, and T-SPOT.TB

TST QFT-GIT T-SPOT.TBPositive 10 17 25*

Negative 85 73 69

Indeterminate NA 5 1

Compared to TST, “Blood tests identified significantly more patients as being infected with MTB …although diagnostic agreement varied …we recommend tailoring application of the new blood IFN-assays for LTBI in different high-risk groups and advise caution in their current use in immunosuppressed patients.” Richeldi L, Losi M, D’Amico R, et al. Chest. 2009;136:198-204.

* p=0.03 vs. QFT-GIT positive

High Risk for Progression/Reactivation: Hematological Malignancies

• T-SPOT.TB results were not affected by white blood cell (WBC) count and were more closely correlated with exposure than TST

Normal WBC Count(n = 68)

Pathological WBC Count(n = 70)

T-SPOT

Positive

Indeterminate

44.6%

6.2%

44.3%

2.8%

TST % Positive 25.9% 14.5%

“T-SPOT.TB test maintains sensitivity and performance in immunosuppressed patients…and can identify infected patients anergic to the tuberculin skin test.” (p. 33)1

Piana F, Codecasa LR, Cavallerio P, et al. Eur Respir J. 2006;28:31-34.

Advantages of IGRAs

• Results are numerical, and thus less subject to reader bias.

• No need for a follow-up visit for reading of results.

• Not affected by BCG vaccination status as they use TB-specific antigens that are not present in BCG.

Thank You!